JPWO2002097160A1 - Film forming method, film forming material, and abrasive film forming sheet - Google Patents

Abstract

First, a brazing sheet is prepared (step S1). The brazing sheet includes a brazing material layer, an adhesive layer, and release paper. The brazing material layer is made of a brazing material. Next, a coating material layer is laminated on the brazing material layer (Step S2). The coating layer is composed of a mixture of coating particles and a binder. As the coating particles, MCrAlY particles and abrasive particles (such as cubic boron nitride particles) are used. Next, the coating material layer is dried (Step S3), the brazing sheet is cut (Step S4), and attached to the moving blade (Step S5). Next, the blade is heated (step S6) to melt the brazing material. The brazing material wets as a liquid phase around the MCrAlY particles and further diffuses through the heat treatment home. Next, a solidified layer is formed by cooling (step S7). A blast treatment (Step S8) is performed on the solidified layer to project the cubic boron nitride particles to complete the abrasive film.

Description

Technical field
The present invention relates to a film forming method for forming a polishing film, an oxidation-resistant film, and the like provided on a member such as a moving blade, a stationary blade, or a shroud in a combustion engine (gas turbine, jet engine, and the like), a steam turbine, and the like. The present invention relates to a material for forming, a sheet for forming an abrasive film, a blade of a gas turbine on which an abrasive film and the like are formed by the method of forming a film, and a gas turbine using the blade.
Background art
In a gas turbine, a clearance of a predetermined size is provided between a moving blade tip and a shroud opposed to the moving blade tip so that they do not contact during operation. If the clearance is too large, the combustion gas leaks from the pressure surface side of the rotor blade to the negative pressure surface side, and the amount of combustion gas that can be used for driving the turbine decreases, resulting in a decrease in the operating efficiency of the gas turbine. Therefore, the clearance is set as small as possible for the purpose of improving the performance of the gas turbine by suppressing the leakage of the combustion gas as much as possible.
However, if the clearance is too small, the tip of the moving blade slides with the shroud due to thermal expansion of the moving blade, eccentricity of the turbine rotor, vibration generated in the entire gas turbine, and the like in the initial stage of gas turbine operation. It may move (so-called initial sliding). Further, when the gas turbine is operated for a long period of time, the shroud exposed to the high-temperature gas gradually undergoes thermal deformation, and the tip of the moving blade and the shroud may also slide (so-called secondary sliding). Ver.)
Generally, the shroud has a coating formed on the inner peripheral surface thereof for the purpose of heat shielding or oxidation prevention. For example, a TBC (Thermal Barrier Coating) may be provided for the purpose of heat insulation, and sometimes an oxidation-resistant coating made of MCrAlY may be provided. Here, M is one or more of iron, nickel, and cobalt. These coatings often have high hardness, so that when the blade tip slides on the inner peripheral surface of the shroud, the blade may be greatly damaged.
Japanese Patent Application Laid-Open Nos. 4-218598 and 9-504340 and U.S. Pat. No. 5,702,574 have an abrasive film in which abrasive particles are dispersed in a matrix made of MCrAlY which is an antioxidant material. A bucket is disclosed. In this rotor blade, for example, cubic boron nitride (CBN) or the like is used as abrasive particles. Cubic boron nitride is a material having high hardness, and therefore, when the blade and the inner peripheral surface of the shroud slide, the abrasive particles made of cubic boron nitride polish the inner peripheral surface of the shroud. Thereby, an appropriate clearance is maintained between the bucket and the shroud.
The abrasive film is obtained by first temporarily attaching abrasive particles to the blade body, and then forming a matrix around the abrasive particles by electrodeposition plating. That is, the matrix is formed by growing the plating layer. Since the growth of the plating layer takes a long time, this forming method is inefficient. Moreover, formation of a matrix by the electrodeposition plating method is generally expensive. Furthermore, electrodeposition plating requires a large-scale facility, and it is difficult to newly install an electrodeposition plating facility from the viewpoint of environmental protection.
Japanese Patent Application Laid-Open No. 10-30403 discloses a method for forming a polishing film in which a matrix is formed by a thermal spraying method. The thermal spraying method is a method of growing a metal layer by spraying a molten metal, and has a feature that the efficiency is higher than that of an electrodeposition plating method. However, in the thermal spraying method, when the abrasive particles are temporarily fixed to the rotor blade body, the electrodeposition plating method is used, so that the above-described problem is caused, and it is difficult to accurately control the thickness of the matrix. Yes, and large-scale thermal spraying equipment is required. When abrasive particles such as cubic boron nitride are dispersed in a metal matrix by a thermal spraying method, the abrasive particles are buried in the molten metal. Particles hardly grind the inner peripheral surface of the shroud. Then, the metal matrix is welded to the inner peripheral surface of the shroud, which may cause damage to the moving blade.
As described above, an oxidation-resistant film made of TBC or MCrAlY may be provided on the inner peripheral surface of the shroud as described above. ), LPPS (Low Pressure Plasma Spray), and D-GUN (Detonation Gun).
The present invention provides a film forming method capable of easily forming an abrasive film, a material for forming a film, a sheet for forming an abrasive film, a blade of a gas turbine in which an abrasive film and the like are formed by the film forming method, and It is an object to provide a gas turbine using a moving blade.
Disclosure of the invention
In order to achieve this object, a method for forming a film according to the present invention includes the following steps (1) to (3).
(1) A laminating step of laminating a brazing material layer mainly composed of a brazing material and a covering material layer mainly composed of a covering material on the front surface or the back surface of a film forming object.
(2) A melting step in which the brazing material layer and the coating material layer are heated to diffuse the coating material and the brazing material while melting and penetrating the brazing material component into the coating material.
(3) A fixing step in which the molten brazing material is solidified and fixed to a film formation target.
In the film forming method according to the present invention, the film is formed by so-called brazing. This method is lower in cost than the plating method and the thermal spraying method, and does not require a large-scale facility, so that there are few restrictions on a construction place.
In this case, as in the film forming method according to the present invention, the thickness ratio between the brazing material and the coating material laminated in the laminating step is preferably 30/70 or more and 70/30 or less. By selecting the volume ratio in this manner, the wax is reliably melted in the coating material in the melting step.
It is preferable that the brazing material contains boron as in the film forming method according to the next invention. This boron diffuses into the coating material in the melting process and lowers the freezing point of the coating material, so even when heated at a relatively low temperature, the coating material melts and once melted, the boron decreases Since the melting point rises, problems such as remelting hardly occur in actual operation.
Preferably, the brazing material is selected from materials whose melting point is lower than the heat treatment temperature of the object to be film-formed, as in the film-forming method according to the following invention. Thus, the melting step can be performed simultaneously with the heat treatment of the film formation target.
The coating material layer used is preferably one in which coating material particles are dispersed in a binder, as in the film forming method according to the following invention. The binder facilitates lamination of the coating material. In addition, since the binder volatilizes almost completely in the melting step, deterioration of the quality of the film due to the binder remaining in the film is suppressed. If a volatile binder is used, the binder is more likely to be volatilized in the melting step, so that the amount of the binder remaining in the film can be reduced and the quality of the film can be further improved. The binder is preferably one that evaporates at a low temperature, and one that also has a certain degree of strength (rigidity) of the coating material after the binder is dried.
As in the film forming method according to the next invention, the mass ratio between the binder and the coating material particles is preferably 15/85 or more and 2/1 or less. Thereby, the formation of the coating material layer is facilitated and dripping of the brazing material in the melting step can be suppressed.
As an example of a preferable coating material layer, a material containing MCrAlY particles and cubic boron nitride particles as main components as in a film forming method according to the following invention can be mentioned. With this coating material layer, an abrasive film is obtained. In this abrasive film, cubic boron nitride functions as abrasive particles, and MCrAlY serves as a matrix to fix the abrasive particles. Further, the MCrAlY matrix suppresses oxidation of the abrasive particles or the blade material.
Further, as in the method for forming a film according to the next invention, from the viewpoint of simultaneously improving the polishing ability and firmly fixing the abrasive particles, the volume ratio between the MCrAlY particles and the cubic boron nitride particles is 以上 or more. It is preferably at most 2/1.
Further, if the abrasive film is formed on the tip of the moving blade of the gas turbine as in the film forming method according to the next invention, the inner peripheral surface of the opposed shroud is polished. Is prevented.
Further, this film forming method may include an exposing step of removing a part of the MCrAlY from the surface of the fixed coating material layer to expose the cubic boron nitride particles as in the film forming method according to the next invention. preferable.
A preferred exposure method is a blast treatment as in the film forming method according to the following invention. In the blasting process, it is preferable to use a blasting material that is harder than the MCrAlY particles and softer than the abrasive particles, as in the film forming method according to the next invention. Thereby, MCrAlY can be efficiently removed from the formed abrasive film, so that the abrasive particles can be sufficiently exposed.
Further, in the blast treatment, it is preferable that the particle size of the blast material is smaller than the particle size of the abrasive particles and smaller than the interval between the abrasive particles as in the film forming method according to the next invention. However, if the particle size is too small, the holding portion of the abrasive particles will be attacked and may fall off. Thus, the dropout of the abrasive particles can be suppressed to a minimum while sufficiently arranging the abrasive particles, so that sufficient polishing performance can be exhibited from the beginning.
Further, as another example of a preferable coating material layer, a material having MCrAlY particles as a main component as in a film forming method according to the following invention can be mentioned. The coating having oxidation resistance and intergranular corrosion resistance obtained by this coating material layer can be formed by various members of a gas turbine through which a high-temperature gas flows, specifically, a moving blade, as in a coating forming method according to the next invention. , Stationary blades and shrouds.
The coating material for forming a film according to the next invention is cubic boron nitride, Al ₂ O ₃ , SiC or other abrasive particles, a metal material having at least oxidation resistance, and a binder. Since the coating material for forming a film contains abrasive particles, a metal material, and a binder, the brazing material is absorbed into a space formed by volatilization of the binder during heat treatment at the time of forming the film. As a result, the flow of brazing to the surroundings can be extremely reduced, so that the quality (uniformity of the film thickness) after the film is formed on the film forming target can be increased. For this reason, the adjustment of the film thickness after the formation of the film can be minimized, and the trouble of forming the film can be reduced.
Further, the film formation target of the present invention includes a blade and a shroud of a gas turbine. However, since such a target is used in an atmosphere in which a high-temperature combustion gas is injected, the target is formed by oxidation thinning. Its life will be shortened. Since the metal material contained in the coating material for forming a film according to the present invention has oxidation resistance, oxidation hardly occurs even in such an atmosphere. Therefore, even when used for a long period of time, the abrasive particles can be more reliably held and stable polishing performance can be exhibited, and the effect of reducing the oxidation thinning of the base material is also obtained. Can be.
In the coating material for forming a film according to the next invention, in the coating material for forming a film, a ratio of the mass of the binder to the mass of the abrasive particles and the metal material is 15/85 or more and 2/1 or less. It is characterized by. This facilitates the formation of the coating material layer, and also suppresses the flow of the brazing material in the melting step.
A coating material for forming a film according to the next invention is characterized in that in the coating material for forming a film, the metal material is MCrAlY. As described above, since the oxidation-resistant MCrAlY is used as the metal material for forming the coating, even if the coating is formed on a moving blade of a gas turbine used in a high-temperature oxidizing atmosphere, polishing is performed for a long time. Since the polishing performance can be maintained by retaining the particles, and the base material is protected from oxidation, a stable gas turbine operation can be performed.
The coating material for forming a film according to the next invention is characterized in that in the coating material for forming a film, the volume ratio between the MCrAlY particles and the abrasive particles is 以上 or more and 2/1 or less. Cubic boron nitride and Al used as abrasive particles ₂ O ₃ Alternatively, if the ratio of SiC or the like is large, the content of MCrAlY is reduced, and not only oxidation resistance is lowered, but also wax tends to be broken during construction. In addition, the retention of the abrasive particles during brazing becomes insufficient, and the particles float. On the other hand, if the ratio of MCrAlY is too large, the polishing ability of the polishing film may be insufficient. From these viewpoints, if the mass ratio is within the above range, it is possible to prevent the occurrence of brazing and improve workability. In addition, since the metal layer that sufficiently retains the abrasive particles has high oxidation resistance, the particles can be stably retained for a long time, the abrasive particles are prevented from falling off, and a highly reliable gas turbine can be operated.
A polishing film forming sheet according to the next invention is characterized in that a brazing material and any one of the above film forming coating materials are laminated. In the sheet for forming an abrasive film, the binder is contained in the coating material for forming the film, so that in the heat treatment at the time of forming the film, the brazing material is sucked into the space where the binder has volatilized. As a result, dripping during the formation of the film can be extremely reduced, so that the quality after forming the film on the object on which the film is formed can be improved. Further, since the correction after the formation of the film is minimal, the trouble of forming the film can be reduced. Furthermore, since the abrasive film can be formed simply by attaching the sheet for forming an abrasive film to the object to be formed and heat-treating the object to be formed, the abrasive film can be formed very easily as compared with the plating method and the thermal spraying method. Can be formed. In addition, if a metal material having oxidation resistance and intergranular corrosion resistance is used as a coating material for forming a film, an abrasive film can be formed on a gas turbine blade or a shroud used in a high-temperature oxidizing atmosphere. Even in this case, stable polishing performance can be maintained by preventing the abrasive particles from falling off. Thus, stable operation of the gas turbine can be achieved.
Further, since the process before the heat treatment is completed only by sticking the sheet for forming an abrasive film on the object on which the film is to be formed, the work becomes extremely easy. Furthermore, since the sheet is a sheet, it can be cut as appropriate in accordance with the shape of the film formation target, so that the film formation target having various shapes can be easily handled.
The sheet for forming an abrasive film according to the next invention is the sheet for forming an abrasive film, wherein the film thickness ratio between the brazing material and the coating material for forming a film is 30/70 or more and 70/30 or less. Features. By selecting the volume ratio in this manner, not only the coating material for forming a film is reliably melted in the melting step, but also the formed film is solid.
The sheet for forming an abrasive film according to the next invention is characterized in that, in the sheet for forming an abrasive film, the brazing material contains boron. As described above, since the brazing filler metal contains boron, in the melting step, the boron diffuses into the coating material for film formation and lowers the freezing point of the coating material for film formation. Even when the coating is performed, the coating material for forming a film melts. Further, after boron is diffused, the melting point of the coating material for forming a film increases, so that the heat resistance of the brazing material increases. This allows the brazing material to be used without re-melting even when used in a high-temperature gas such as a rotor blade or a shroud of a gas turbine.
The sheet for forming an abrasive film according to the next invention is characterized in that in the sheet for forming an abrasive film, the brazing material is selected from a material having a melting point lower than a heat treatment temperature of a film formation target. I do. This allows the melting step to proceed simultaneously with the heat treatment of the film formation target.
The sheet for forming an abrasive film according to the next invention is characterized in that, in the sheet for forming an abrasive film, an adhesive layer is further formed on the brazing material. For this reason, if only this abrasive film forming sheet is prepared, the processing before heat treatment is completed only by sticking this abrasive film forming sheet to the film forming object, and the gluing becomes unnecessary, and the glue is not required. There is no need to wait for drying. Thereby, the trouble of forming the film can be further reduced.
A moving blade of a gas turbine according to the next invention is characterized in that a film is formed on a tip portion by any one of the film forming methods described above. Therefore, an abrasive film can be formed extremely easily as compared with the plating method and the thermal spraying method. As a result, the time required for forming the film can be significantly reduced as compared with the film forming method, and the manufacturing cost can be reduced.
The blade of the gas turbine according to the next invention is characterized in that any one of the above-mentioned sheets for forming an abrasive film is attached to a tip end portion. For this reason, since a polishing film can be formed only by performing a necessary heat treatment on the rotor blade, the polishing film can be formed extremely easily as compared with the plating method and the thermal spraying method. As a result, the time required for forming the film can be significantly reduced as compared with the film forming method, and the manufacturing cost can be reduced.
A gas turbine according to the next invention is a compressor that compresses air to produce combustion air, and a combustor that generates high-temperature combustion gas by reacting combustion air and fuel produced by the compressor. And a turbine driven by injection of combustion gas from the combustor to the moving blade.
For this reason, if only a heat treatment facility is provided, an abrasive film can be easily formed, so that the facility for forming the film can be simpler than the plating method and the thermal spraying method. Therefore, even if there is no plating equipment near the gas turbine plant, if a heating furnace used for heat treatment is provided, an abrasive film can be easily formed, so that an abrasive film can be formed again on the rotor blades and the like on the spot. You can also. Thus, even if the abrasive film is damaged, it can be easily repaired.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited by the embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.
FIG. 1 is a flowchart illustrating a film forming method according to an embodiment of the present invention. This method of forming a film is applied when a relatively simple device (for example, a high-vacuum heating furnace) is used to form an abrasive film on the tip of a moving blade of a gas turbine. In this film forming method, first, a brazing sheet is prepared (step S1). FIG. 2 (a) is an enlarged sectional view showing a part of the brazing sheet indicated generally by reference numeral 1. The brazing sheet 1 includes a brazing material layer 3 on the upper side in the figure, an intermediate adhesive layer 5 as an adhesive layer, and a release paper 7 on the lower side. Needless to say, the brazing material layer 3 is made of a brazing material. In addition, if the adhesive layer 5 and the release paper 7 on the lower side are provided, the release paper 7 can be peeled off and the brazing sheet 1 can be stuck on the object on which the film is to be formed. Here, the thickness of the brazing material layer 3 is generally about 0.05 mm to 1.00 mm. Further, the brazing material layer 3 may not be a single sheet, and may be used by laminating two or three sheets. The intermediate adhesive layer 5, which is an adhesive layer, and the release paper 7 on the lower side may be provided as necessary. When these are not used, the film-forming target is formed by means such as sticking a binder as a paste. What is necessary is just to stick the sheet 1 to an object.
Preferred brazing materials include those containing about 2.75-3.50% by mass of boron (B) and containing nickel (Ni) as a main component. This brazing material usually contains about 6 to 8% by weight of chromium (Cr), about 4 to 5% by weight of silicon (Si), and about 2.5 to 3.5% by weight of iron (Fe). Is included. The brazing sheet 1 preferably does not become hard even after a long period of time. Specific examples of the brazing sheet 1 include BNi-2 (JIS standard).
This brazing sheet 1 is commercially available in which an adhesive layer 5 and a release paper 7 are preliminarily laminated on a brazing material layer 3, and the brazing material is composed of 83 mass% nickel, 7 mass% chromium, and 3 mass% It contains boron, 4% by weight of silicon and 3% by weight of iron.
Next, a coating material layer 9 shown in FIG. 2B is formed on the brazing sheet 1 (Step S2). It is also possible to separately form and cut the covering material layer 9 and the sheet 1 and to bond them later with a binder or the like. However, in order to prevent cracks such as cutting in multiple steps, a soft BNi- As a multi-layer with two layers, the cutability of the entire sheet is improved.
The coating material layer 9 is formed by applying a mixture of the coating material particles and the binder 11 to the surface of the brazing material layer 3. First, a mixture of the coating material particles and the binder 11 flows on the brazing material layer 3. Next, excess mixture is scraped off while the mixture is stretched into a sheet shape by a blade or the like, and the mixture is coated to a predetermined thickness in consideration of a shrinkage allowance when the mixture is dried. The coating material layer 9 is dried after coating (step S3), and is naturally dried usually for about one day. Drying volatilizes the binder 11 to some extent. The thickness of the coating material layer 9 is reduced by volatilization.
The predetermined thickness of the coating material layer 9 after coating may be about 0.10 to 1.00 mm, but after the coating material layer 9 is dried, the thickness of the coating material layer 9 is used as a guide to determine the film thickness of the brazing sheet 1. It should be less than the thickness. For this reason, it is preferable to appropriately change the thickness of the coating material layer 9 after applying the mixture according to the mixing ratio of the binder 11 and the component ratio of the coating material layer 9.
Here, in this embodiment, MCrAlY particles 13 which are a metal material having oxidation resistance and intergranular corrosion resistance are used as coating particles, and cubic boron nitride particles 15 are used as abrasive particles. Hereinafter, when simply referred to as coating material particles, both of these particles are referred to. A binder is mixed with the coating material particles and the abrasive particles to form a coating material for forming a coating material layer 9.
MCrAlY is an alloy containing iron (Fe), nickel (Ni) or cobalt (Co), chromium (Cr), aluminum (Al), and yttrium (Y) as main components, and has oxidation resistance and resistance to oxidation. It has intergranular corrosion properties. Here, it is preferable to increase the content of Cr and Al in order to improve the intergranular corrosion resistance and the oxidation resistance in consideration of the fact that MCrAlY is diluted by the Ni solder after the film is formed. However, it should be noted that if these amounts, especially Al, are too large, the brazing properties deteriorate. Further, in order to improve oxidation resistance, intergranular corrosion resistance and brazing properties, Ta, Re, Hf, Si, etc. can be added in addition to Cr and Al.
In addition, it is necessary that the surface of the MCrAlY particles be free from impurities for brazing, such as O and N, as much as possible. Preferably, MCrAlY having a particle size in the range of 10 to 100 μm is used at random in order to increase the filling rate. However, if the particle size is too small, the surface area increases, and the amount of impurities such as O and N increases.
On the other hand, as the cubic boron nitride particles 15, those commercially available from General Electric, De Beers, Showa Denko KK, Sumitomo Denko KK, and the like can be used. Cubic boron nitride is classified into single crystal and polycrystal, and there is also a high-purity product. Each of them can be used properly, but it is clear that cubic boron nitride coated with TiN or the like has excellent brazing properties. It has become. When the cubic boron nitride is coated in this manner, the wettability between the cubic boron nitride and the brazing material is improved, and the cubic boron nitride particles 15 can be sufficiently embedded in the brazing material. As a result, the falling of the cubic boron nitride particles 15 can be suppressed, so that the TBC layer or the like of the shroud can be stably cut off, welding between the blade tip and the shroud can be prevented, and a highly reliable operation can be performed.
Further, cubic boron nitride coated with Co or Ni, or cubic boron nitride coated with TiN or a Ti compound can be used. It is desirable to appropriately select these depending on the type of MCrAlY particles forming the coating material layer 9.
Further, instead of the cubic boron nitride particles 15, for example, Al ₂ O ₃ And SiC can also be used as abrasive particles. In order to improve the wettability with the brazing material, Al ₂ O ₃ Al and SiC are also used when coated Al ₂ O ₃ It is preferable to use SiC. And Al ₂ O ₃ From the viewpoint of improving the film forming property with respect to TiN and TiN and the wettability with respect to the MCrAlY material, these coating materials include, for example, Al particles as abrasive particles. ₂ O ₃ When using, Co, Cr, Ni and the like can be mentioned. When SiC is used as abrasive particles, AlN, TiN, AlN may be used as a coating material to suppress the reaction between SiC and Cr during brazing. ₂ O ₃ And the like.
Volume V of MCrAlY particles 13 _M And the volume V of the cubic boron nitride particles 15 _C Volume ratio V _M / V _C Is preferably 30/70 or more and 70/30 or less. If the ratio of the cubic boron nitride particles 15 is large, the porosity in the brazing sheet 1 increases, and the amount of the binder increases. As a result, brazing or deformation tends to occur. When the ratio of the cubic boron nitride particles 15 exceeds 70%, that is, the volume ratio V _M / V _C Is smaller than 30/70, the density of the cubic boron nitride particles 15 is too large, and it becomes difficult to perform electric discharge machining from the film. Further, since the oxidation resistance is also reduced, the holding power of the cubic boron nitride particles 15 is also reduced, and the cubic boron nitride particles 15 may fall off. From these viewpoints, the volume ratio V _M / V _C Is more preferably 1/2 or more, and furthermore, the ratio of the cubic boron nitride particles 15 is 60% or less, that is, the volume ratio V _M / V _C Is preferably 40/60 or more from the viewpoint of cost. On the other hand, the volume ratio V _M / V _C Exceeds 70/30, the polishing ability of the abrasive film may be insufficient. From this viewpoint, the volume ratio V _M / V _C Is more preferably 2/1 or less, particularly preferably 60/40 or less. Therefore, the most preferable volume ratio V _M / V _C Is 40/60 or more and 60/40 or less. At the time of actual work, since the specific gravity (density) of each material is known, the sheet 1 is created by mass management.
Here, the cubic boron nitride particles 15 are high in high-temperature hardness and excellent in machinability, but are also known to disappear in a high-temperature oxidizing atmosphere in a short time. ₂ O ₃ It is necessary to mix them. Instead of the cubic boron nitride particles 15 or together with the cubic boron nitride particles 15, ₂ O ₃ These volume ratios can also be applied when using TiN or TiN.
Although various kinds of binders can be used, it is preferable to use a binder which volatilizes at a particularly low temperature. Since the volatile binder 11 is volatilized in a drying step and a melting step described in detail later, it hardly remains in the abrasive film. Therefore, the quality of the abrasive film is not adversely affected. Further, a space is formed after the volatile binder 11 has volatilized. In the melting step described later, the metal braze is sucked into these gaps by capillary action, so that dripping can be extremely reduced in the melting step described later. As a result, the deterioration of the quality of the moving blade due to the dripping is suppressed, and the treatment of the dripping (mainly, the application of the stop-off) is hardly required, so that the work of construction can be improved.
Here, as the preferred volatile binder 11, an organic binder can be suitably used, and among them, a cellulose binder is more preferred because of its good brazing property. It is preferable to use a binder to which a plasticizer is added because the polishing film-forming sheet 1a described below has flexibility and can be easily cut, and the like, so that the workability can be improved.
Mass m of volatile binder 11 _B And mass m of coating material particles 13 and 15 _C And mass ratio m _B / M _C Is preferably 15/85 or more and 2/1 or less. Mass ratio m _B / M _C Is less than the lower limit of the above range, it may be difficult to apply a mixture of the coating material particles 13 and 15 and the binder 11. From this viewpoint, the mass ratio m _B / M _C Is more preferably 20/80 (１ ／) or more, further preferably １ ／ or more. On the other hand, mass ratio m _B / M _C Exceeds the upper limit of the above range, dripping of the brazing filler metal is liable to occur during the heat treatment of the film formation target. From this viewpoint, the mass ratio m _B / M _C Is more preferably 60/40 or less, particularly preferably 40/60 or less. Accordingly, the mass ratio m between the preferred volatile binder 11 and the coating material particles 13 and 15 is m. _B / M _C Is 20/80 or more and 40/60 or less.
The thickness ratio between the brazing material and the coating material is preferably 30/70 or more and 70/30 or less. When the film thickness ratio is less than the lower limit of the above range, the wax does not penetrate into the coating material in the melting step, so that the wax is easily cut. In this respect, the film thickness ratio is particularly preferably equal to or greater than 60/40. After the brazing sheet 1 is formed, the brazing sheet 1 is dried at normal temperature to facilitate the cutting operation and to volatilize excess binder. If possible, it is desirable to dry for a whole day or more in a constant temperature room where temperature and humidity are controlled.
Next, the brazing sheet 1 on which the coating material layer 9 is laminated (hereinafter, referred to as an abrasive film forming sheet 1a) is cut into a predetermined shape and dimensions (step S4). The means for cutting is not particularly limited, but it is preferable to use a stencil and an ultrasonic cutter because the abrasive film forming sheet 1a is highly brittle. Then, the release paper 7 is peeled off from the abrasive film-forming sheet 1a cut into a predetermined shape and size, and is adhered to the tip of a moving blade, which is a film-forming object (Step S5).
Since the abrasive film forming sheet 1a is cut into a blade shape, most of the sheet 1a remains as a piece. Since the very expensive cubic boron nitride is contained in the abrasive film forming sheet 1a, it is necessary to recover the cubic boron nitride. However, the surface of the cubic boron nitride is provided with a coating for improving brazing properties, and it is important to recover the coating without damaging it. Therefore, at the time of recovery, the scraps of the abrasive film forming sheet 1a are boiled and immersed in a NaOH solution having a concentration of about 10% for about 1 to 5 hours to dissolve the binder, and then subjected to ultrasonic cleaning with pure water and filtration. By washing with pure water and classifying and drying, only cubic boron nitride can be recovered. Here, the pure water ultrasonic cleaning is performed three times, for example, for about 10 to 30 minutes, and the drying is performed, for example, at 120 ° C. for about one hour.
Prior to the application of the abrasive film forming sheet 1a, it is preferable to apply a pretreatment such as blasting or washing with a solvent such as trichloroethylene or acetone to the tip of the blade. This is because the tip of the moving blade on which the film is formed by the pretreatment is roughened, and the oils and fats at the portion where the film is formed are removed, so that the adhesion between the film and the tip of the moving blade is improved.
Here, the blade tip may be provided with a hole for ejecting a cooling medium such as cooling air or cooling steam from the internal cooling passage. Therefore, if this hole is closed when the abrasive film forming sheet 1a is attached to the tip of the moving blade, the cooling medium cannot be ejected during the operation of the gas turbine, and the cooling of the moving blade may be insufficient. There is. Therefore, the sheet 1a for forming an abrasive film is stuck so as to avoid the portion of the hole from which the cooling medium is ejected. However, when the hole size is small and large, it is difficult to avoid this hole. In addition, since the sheet 1a for forming an abrasive film is easily cut before the heat treatment, it is difficult to secure a hole in the sheet before attaching the sheet. For this reason, it is possible to form holes by electric discharge machining or the like after the formation of the film. Holes can be formed by electric discharge machining before or after cubic boron nitride particles are exposed.
Next, the abrasive film forming sheet 1a is heated together with the blade body (step S6). For heating, a vacuum heating furnace is usually used. The heating conditions are determined in consideration of the material of the blade body, the type of brazing material, and the like. For example, when the material of the rotor blade body is a rotor blade base material (Ni-based superalloy or the like) and the above-mentioned BNi-2 is used as the sheet 1 used for the abrasive film forming sheet 1a, first, it is 10 hours or more. Then, the temperature of the vacuum heating furnace is raised from room temperature to about 600 ° C. As described above, since the binder 11 in the abrasive film forming sheet 1a is positively volatilized at a low temperature by heating over a long time, components of the binder 11 that easily thermally expand do not remain at a high temperature. Thereby, wrinkles due to thermal elongation do not occur, and the quality of the formed abrasive film can be increased. The degree of vacuum at this time is 10 ^-5 It is preferable that the degree of vacuum be higher than torr. Next, the temperature is raised to 1000 ° C. or higher over about 2 hours, and this state is maintained for a necessary time. As a result, almost all of the binder 11 is volatilized from the coating material layer 9, and a space is created in the coating material layer 9 after the binder 11 is volatilized.
Since the melting point of this brazing material is about 1000 ° C., the brazing material is melted by heating at 1000 ° C. or more. The brazing material that has become liquid by this heating penetrates into the space in the coating material layer 9 by capillary action and is absorbed into this space. Further, boron as a brazing filler metal also diffuses into the MCrAlY particles 13 in the coating material layer 9. Since boron lowers the solidification point of MCrAlY, MCrAlY is in a semi-molten state and is easily diffused with the surrounding brazing material.
Next, the inside of the vacuum heating furnace is cooled to 500 ° C. or lower by introducing argon gas or nitrogen gas (step S7). As a result, the strength required for the Ni alloy as the base material is obtained, and the solidified layer 21 in which the cubic boron nitride particles 15 are dispersed in the MCrAlY matrix 19 as shown in FIG. Is formed. Since the boron has disappeared to some extent by the temperature control at 1000 ° C. or more, the melting point of the matrix 19 rises to a temperature at which there is no practical problem. With this heat history, heat treatment (stabilization treatment) necessary for the strength of the moving blade is performed. That is, by selecting a brazing material having a melting point lower than the heat treatment temperature of the moving blade, the melting of the coating material and the heat treatment of the moving blade are simultaneously completed in the melting step.
In general, cubic boron nitride has a lower specific gravity than the brazing material. Therefore, if both are mixed in advance, the cubic boron nitride particles 15 float on the surface layer in the liquid brazing material, and The dispersion of the crystalline boron nitride particles 15 becomes non-uniform. Also, dripping of the molten brazing material is likely to occur. In a preferred embodiment of the present invention, the brazing material layer 3 and the coating material layer 9 are sequentially laminated on the blade tip 17 and the two are mixed by the capillary phenomenon as described above. For this reason, the cubic boron nitride particles 15 are not lifted because they are held by the MCrAlY in the coating material layer 9, so that the dispersion of the cubic boron nitride particles 15 is uniform, and the dripping of the brazing filler metal is suppressed.
Next, a blast process is performed on the solidified layer 21 (step S8). In the blast processing, blast particles are sprayed on the surface of the matrix 19. By this blasting process, a portion of the matrix 19 near the surface is removed as shown in FIG. 2 (d). Since the cubic boron nitride particles 15 are hardly removed by the blast treatment according to the present invention, the cubic boron nitride particles 15 protrude from the matrix 19 (so-called “index”). Thus, the polishing film 23 is completed. In FIG. 2 (d), the boundary between the abrasive film 23 and the blade tip 17 is clearly defined, but in an actual blade, the boundary between the two is ambiguous due to diffusion during heating. .
In order to remove the portion near the surface of the matrix 19 in preference to the cubic boron nitride particles 15 by blasting, blast particles having a lower hardness than the cubic boron nitride particles 15 and a higher hardness than the matrix 19 are used. Preferably, it is used. That is, when the Vickers hardness of the matrix 19 is H1, the Vickers hardness of the cubic boron nitride particles 15 is H2, and the Vickers hardness of the blast particles used in the blasting process is H3, H1, H2 and H3 are represented by the following formula (I). It is preferable to satisfy the relationship shown in (1).
H1 <H3 <H2 (I)
When MCrAlY is used for the cubic boron nitride particles 15 and the matrix 19, as such blast particles, for example, Al ₂ O ₃ Can be used.
When the diameter of the blast particles is too large, the cubic boron nitride particles 15 are insufficiently exposed. On the other hand, if the diameter of the blast particles is too small, the roots holding the cubic boron nitride particles 15 will advance too much, and the cubic boron nitride particles 15 will fall off the coating material layer 9. Therefore, it is preferable to use blast particles having a size smaller than the interval between the cubic boron nitride particles 15 and having such a size that the root holding the cubic boron nitride particles 15 is not attacked. In this example, the average particle size of Al is 50 μm. ₂ O ₃ Although microblast using particles is used, it is desirable to appropriately select the diameter of the blast particles to be used according to the particle size and the interval of the cubic boron nitride particles 15. For example, when the spacing between the cubic boron nitride particles 15 is large and the surface is rough, it is preferable to use larger blast particles. Also, in the abrasive film, the abrasive particles have Al ₂ O ₃ When ZrO or SiC is used, ZrO ₂ Preferably, glass beads or the like are used as blast particles.
FIG. 3 is a perspective view showing the rotor blade 25 on which the abrasive film 23 is formed by the forming method of FIG. The moving blade 25 includes a main body 27 and a protruding portion 29 extending from an end thereof, and the polishing film 23 is coated on an upper surface of the protruding portion 29 which is a tip of the moving blade. Although not shown, in the gas turbine, the inner peripheral surface of the shroud is located to face the abrasive film 23. The inner peripheral surface of the shroud is polished by the abrasive film 23 when the bucket 25 and the shroud slide. There is a moving blade without the ridge portion 29, but in that case, an abrasive film can be formed on the tip of the moving blade.
The average particle diameter of the cubic boron nitride particles 15 is preferably about 50 to 200 μm. When the average particle diameter is less than 50 μm, the polishing ability of the abrasive film 23 may be insufficient. In this respect, the average particle diameter is particularly preferably equal to or greater than 80 μm. On the other hand, when the average particle diameter exceeds 200 μm, not only the film thickness of the abrasive film 23 becomes excessive, but also the oxidation resistance of the abrasive film 23 becomes insufficient. In this respect, in the case of a gas turbine blade, the average particle diameter is particularly preferably equal to or less than 170 μm. Therefore, the most preferred average particle diameter range is 80-170 μm.
FIG. 4 is an enlarged sectional view showing a part of the moving blade 25 of FIG. As described above, the cubic boron nitride particles 15 protrude from the matrix 19. In this drawing, what is indicated by a double-pointed arrow p is the protrusion size of the cubic boron nitride particles 15. Assuming that the average particle diameter of the cubic boron nitride particles 15 is D and the average value of the protrusion dimensions p of all the cubic boron nitride particles 15 projecting from the matrix 19 (that is, the average protrusion dimension) is P, the average particle diameter The ratio of the average protrusion dimension P to D is preferably 25% or more and 70% or less. If the ratio is less than 25%, the polishing ability of the polishing film 23 may be insufficient. In this respect, the ratio is more preferably equal to or greater than 30%. Conversely, if this ratio exceeds 70%, the cubic boron nitride particles 15 may easily fall off the matrix 19. In this respect, the ratio is more preferably equal to or less than 60%. Therefore, the most preferable ratio range is 30 to 60%.
The thickness of the matrix 19 (the portion indicated by the double-headed arrow T in FIG. 4) is preferably 50 μm or more. If the thickness of the matrix 19 is less than 50 μm, not only the retention of the cubic boron nitride particles 15 in the abrasive film 23 becomes insufficient, but also the distribution of the cubic boron nitride particles 15 cannot be arranged in a random manner. In addition, the long-term high-temperature durability of the polishing film 23 is reduced.
In the present invention, an abrasive film forming sheet 1a, which is a brazing sheet 1 on which a coating material layer 9 is laminated, is used. Then, this is cut into a predetermined shape and attached to a film-forming object, and then the film-forming object is subjected to a heat treatment to form an abrasive film 23 (see FIG. 3) on the film-forming object. Next, the abrasive film 23 is subjected to blast processing to find the cubic boron nitride particles 15, and the abrasive particles are projected from the abrasive film 23. After the abrasive film-forming sheet 1a is manufactured in this manner, the sheet is simply cut into a predetermined shape and attached to the film-forming object, and the necessary heat treatment is applied to the film-forming object. Can be formed. In addition, since the blasting is also used for locating the abrasive particles, the abrasive particles can be easily projected. For this reason, an abrasive film can be formed extremely easily as compared with the conventional plating method and thermal spraying method.
For example, when an abrasive film is formed on the tip of a certain gas turbine blade, the film forming method according to the present invention reduces the construction cost to 1/3 to 1/4 compared to the conventional plating method. Can be suppressed. Also, the time required for construction can be reduced to 1/3 or less. As described above, a great effect of reducing the construction cost and the effect of shortening the construction period are obtained, and therefore, it is extremely useful when forming an abrasive film on a large number of moving blades. Further, since large-scale equipment such as a plating method is not required, the cost required for capital investment can be reduced. Further, since no plating waste liquid is generated unlike the plating method, the environmental load can be extremely reduced.
Furthermore, if heating equipment such as a vacuum heating furnace is prepared, an abrasive film can be formed only by supplying the abrasive film forming sheet 1a, so that the heat treatment and the preparation of the sheet need not necessarily be performed in the same place. There is no. For this reason, since the degree of freedom of construction can be increased, for example, even in a gas turbine plant installed in a place where there is no construction facility nearby, a heating facility is provided and the abrasive film forming sheet 1a is periodically supplied. Then, re-coating can be done on the spot.
In the above description, the case where cubic boron nitride and MCrAlY are used as the coating material is described as an example, but only MCrAlY may be used as the coating material. In this case, the obtained film becomes an oxidation resistant film. The oxidation resistant coating is suitable for a moving blade, a stationary blade, or a shroud of a gas turbine.
FIG. 5 is an explanatory view showing a gas turbine provided with a gas turbine rotor blade having an abrasive film formed at the tip portion by the film forming method according to the present invention. The air taken in from the air inlet 50 is compressed by the compressor 51 to be high-temperature and high-pressure compressed air and sent to the combustor 52. In the combustor 52, a gas fuel such as natural gas or a liquid fuel such as light oil or light heavy oil is supplied to the compressed air to burn the fuel and generate high-temperature and high-pressure combustion gas. The high-temperature and high-pressure combustion gas is guided to the combustor transition piece 53 and then injected into the turbine 54.
The turbine 54 is provided with a moving blade 25 (see FIG. 3) having the abrasive film 23 formed on the tip thereof by the film forming method according to the present invention. The blade 25 has a coating according to the present invention formed on the tip thereof. When the operation of the gas turbine 100 is started, so-called initial sliding occurs due to thermal expansion of the moving blade, and the tip of the moving blade 25 may come into contact with the inner wall of the shroud 55 in some cases. After a certain period of time has elapsed from the start of operation, the tip of the moving blade 25 may come into contact with the inner wall of the shroud 55 due to deformation of the shroud 55, causing so-called secondary sliding. In any case, since abrasive particles are firmly brazed to the tip of the rotor blade 25 by the film forming method according to the present invention, a film such as TBC (not shown) formed on the inner wall of the shroud 55 is formed. ) Can be removed. Thus, welding of the rotor blades 25 can be prevented, so that the gas turbine 100 can be stably operated. Note that cubic boron nitride functions for initial sliding and SiC or Al, which has excellent long-term stability at high temperatures for secondary sliding. ₂ O ₃ Preferably function. Therefore, it is more desirable to use a mixture of them in order to ensure long-term reliability of the gas turbine.
Further, since the coating is formed on the tip of the blade 25 according to the present invention by brazing, cubic boron nitride and other abrasive particles can be distributed in the shape of a shark tooth. For this reason, even if the abrasive particles on the surface layer spill out, the next abrasive particles appear, so that the TBC or the like formed on the inner wall of the shroud 55 stably until the abrasive film 23 (see FIG. 3) disappears. The film can be scraped off. As a result, a more reliable operation can be performed than using a rotor blade on which a film is formed by a conventional plating method or a thermal spraying method.
As can be seen from the above description, the film forming method according to the present invention includes the following steps (1) to (3);
(1) a laminating step of laminating a brazing material layer mainly composed of a brazing material and a coating material layer mainly composed of a coating material on the front surface or the back surface of the film formation target;
(2) a melting step of heating the laminated brazing material layer and the coating material layer to diffuse and diffuse the coating material and the brazing material while melting and penetrating the brazing material component into the coating material;
(3) a fixing step in which the molten brazing material is solidified and fixed to the film formation target;
A film is formed by so-called brazing. This method is lower in cost than the plating method and the thermal spraying method, and does not require a large-scale facility.
Further, in the film forming method according to the present invention, since the thickness ratio of the brazing material and the coating material laminated in the laminating step is set to 30/70 or more and 70/30 or less, the coating material is reliably melted in the melting step. In addition to this, the formed film becomes firm and its characteristics can be improved.
Further, in the film forming method according to the present invention, since the brazing material contains boron, the boron diffuses into the coating material in the melting step and lowers the solidification point of the coating material, so that the material is heated at a relatively low temperature. In this case, the coating material can be reliably melted at low cost.
Further, in the film forming method according to the present invention, since the brazing material whose melting point of the brazing material is lower than the heat treatment temperature of the film forming object is selected, the melting step can be performed simultaneously with the heat treatment of the film forming object. . Thereby, the work efficiency of the film formation can be improved.
Further, in the film forming method according to the present invention, since the coating material layer in which the coating material particles are dispersed in the binder is used, not only the function of the binder facilitates the lamination of the coating material, but also Since the binder volatilizes almost completely in the melting step, it is possible to suppress the deterioration of the film quality due to the binder remaining in the film.
Further, in the film forming method according to the present invention, since the mass ratio between the binder and the coating material particles is set to 15/85 or more and 2/1 or less, the formation of the coating material layer is facilitated, and the liquid of the brazing material in the melting step is further improved. Anyone can be suppressed and workability can be improved.
In the method for forming a film according to the present invention, MCrAlY particles and cubic boron nitride particles are used as main components. In the abrasive film obtained by this coating material layer, cubic boron nitride functions as abrasive particles, and MCrAlY serves as a matrix to fix the abrasive particles. The matrix of MCrAlY can suppress the oxidation of the abrasive particles.
Further, in the film forming method according to the present invention, the volume ratio between the MCrAlY particles and the cubic boron nitride particles is set to not less than 1/2 and not more than 2/1. For this reason, the polishing ability of the abrasive film is improved, and the abrasive particles can be securely fixed.
Further, in the film forming method according to the present invention, since the abrasive film is formed at the tip of the moving blade of the gas turbine, cubic boron nitride of the abrasive film is polished on the inner peripheral surface of the shroud opposed thereto, and the rotating blade is Damage can be prevented.
Further, the method for forming a film according to the present invention includes an exposing step of exposing the cubic boron nitride particles by removing a part of the MCrAlY from the surface of the fixed coating material layer. In the method of forming a film according to the present invention, blasting is used in the exposing step for exposing the cubic boron nitride particles. Thereby, the cubic boron nitride particles can be appropriately spotted.
In the method for forming a film according to the present invention, in the blasting, a blast material that is harder than the MCrAlY particles and softer than the abrasive particles is used. As a result, MCrAlY can be efficiently removed from the formed abrasive film, so that the abrasive particles can be sufficiently obtained.
Further, in the film forming method according to the present invention, in the blast treatment, a blast material having a particle size smaller than the particle size of the abrasive particles and smaller than the space between the abrasive particles is used. Thus, the dropout of the abrasive particles can be suppressed to a minimum while sufficiently arranging the abrasive particles, so that sufficient polishing performance can be exhibited from the beginning.
Further, as another example of a preferable coating material layer, a material containing MCrAlY particles as a main component as in the following film forming method according to the present invention can be mentioned. The oxidation resistant film obtained by this coating material layer is suitable for various members of a gas turbine through which a high-temperature gas flows, specifically, a moving blade, a stationary blade, and a shroud, as in the film forming method according to the present invention described below. Can be used for
Further, in the coating material for forming a film according to the present invention, since the abrasive particles, at least a metal material having oxidation resistance and a binder are included, during the heat treatment at the time of forming the film, the binder is volatilized. The brazing material is absorbed into the space. As a result, dripping of the brazing filler metal can be extremely reduced, so that the quality after forming the film on the film formation target can be improved. Further, since the metal material has oxidation resistance, oxidation is unlikely to occur even in a high-temperature combustion gas atmosphere in which a rotor blade of a gas turbine is used. As a result, even when used for a long period of time, the abrasive particles can be more reliably held and stable polishing performance can be exhibited, and the oxidation thinning of the base material can be reduced, so that a more stable gas turbine operation can be performed. .
Further, in the coating material for forming a film according to the present invention, in the coating material for forming a film, the ratio of the mass of the binder to the mass of the abrasive particles and the metal material is 15/85 or more and 2/1 or less. This facilitates the formation of the coating material layer, and can suppress dripping in the melting step.
In the coating material for forming a film according to the present invention, the metal material included in the coating material for forming a film is MCrAlY. Since MCrAlY, which has oxidation resistance and intergranular corrosion resistance, is used as described above, even if a film is formed on a moving blade of a gas turbine used in a high-temperature oxidizing atmosphere, the abrasive particles are retained for a long time. Polishing performance can be maintained. Thus, stable operation of the gas turbine can be achieved.
Further, in the coating material for forming a film according to the present invention, in the coating material for forming a film, the volume ratio between the MCrAlY particles and the abrasive particles is 以上 or more and 2/1 or less. For this reason, it is possible to prevent the occurrence of brazing and improve workability. Further, since the abrasive particles can be sufficiently fixed, the falling of the abrasive particles can be suppressed, and the gas turbine can be operated with high reliability.
Further, the abrasive film-forming sheet according to the present invention is formed by laminating a brazing material and any one of the above-mentioned film-forming coating materials. For this reason, since the abrasive film can be formed only by attaching the sheet for forming an abrasive film to the object to be formed and then heat-treating the object to be formed, the abrasive film can be formed very easily as compared with the plating method and the thermal spraying method. An abrasive film can be formed. Further, since the process before the heat treatment is completed only by sticking the sheet for forming an abrasive film on the object on which the film is to be formed, the work becomes extremely easy. Furthermore, since the sheet is a sheet, it can be cut as appropriate in accordance with the shape of the film formation target, so that the film formation target having various shapes can be easily handled.
In the sheet for forming an abrasive film according to the present invention, in the sheet for forming an abrasive film, the thickness ratio between the brazing material and the coating material for forming the film is set to 30/70 or more and 70/30 or less. For this reason, not only the coating material for forming a film is reliably melted in the melting step, but also the formed film is firm.
Further, in the abrasive film forming sheet according to the present invention, in the above abrasive film forming sheet, the brazing filler metal contains boron. As described above, since boron is contained in the brazing material, in the melting step, the boron diffuses into the coating material for film formation and lowers the freezing point of the coating material for film formation. Thereby, the coating material for forming a film is melted even when heated at a relatively low temperature. Further, after boron diffusion, the melting point of the coating material for forming a film increases, so that the heat resistance of the brazing material increases. This allows the brazing material to be used without melting even when used in a high-temperature gas such as a rotor blade or a shroud of a gas turbine.
In the polishing film forming sheet according to the present invention, in the polishing film forming sheet, the brazing material is selected from materials whose melting point is lower than the heat treatment temperature of the film forming object. This allows the melting step to proceed simultaneously with the heat treatment of the film formation target.
In the sheet for forming an abrasive film according to the present invention, an adhesive layer is further formed on the brazing material in the sheet for forming an abrasive film. For this reason, if only this abrasive film forming sheet is prepared, the processing before heat treatment is completed only by sticking this abrasive film forming sheet to the film forming object, and the gluing becomes unnecessary, and the glue is not required. There is no need to wait for drying. Thereby, the trouble of forming the film can be further reduced.
Further, in the blade of the gas turbine according to the present invention, the abrasive film is formed on the tip portion by any one of the film forming methods described above. For this reason, the abrasive film can be formed extremely easily as compared with the plating method and the thermal spraying method, so that the time required for forming the film can be greatly reduced as compared with the film forming method, and the manufacturing cost can be reduced.
Further, in the moving blade of the gas turbine according to the present invention, any one of the above-mentioned sheets for forming an abrasive film is attached to a tip portion. For this reason, since a polishing film can be formed only by performing a necessary heat treatment on the moving blade later, the polishing film can be formed extremely easily as compared with the plating method and the thermal spraying method. As a result, the time required for forming the film can be significantly reduced as compared with the film forming method, and the manufacturing cost can be reduced.
Further, in the gas turbine according to the present invention, the turbine driven by the injection of the combustion gas from the combustor is provided with the moving blade. For this reason, as long as the heat treatment equipment is provided, the abrasive film can be easily formed on the rotor blade. Even if there is no plating equipment near the operation site of the gas turbine, if the heating furnace used for the heat treatment is provided. An abrasive film can be easily formed. As a result, the abrasive film can be formed again on the moving blade or the like on the spot, so that the moving blade can be easily repaired.
Industrial applicability
As described above, the film forming method, the film forming material, the abrasive film forming sheet of the present invention, the blade of the gas turbine having the abrasive film formed by the film forming method, and the blade were used. The gas turbine is useful for forming an abrasive film, an oxidation-resistant film, and the like provided on members such as a moving blade, a stationary blade, and a shroud of a combustion engine (gas turbine, jet engine, and the like) and a steam turbine. It is suitable for easily forming these films.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a film forming method according to an embodiment of the present invention, and FIG. 2 is a schematic diagram for explaining various steps in the film forming method of FIG. FIG. 4 is a perspective view showing a moving blade on which an abrasive film is formed by the forming method of FIG. 1, FIG. 4 is an enlarged sectional view of a part of the moving blade shown in FIG. FIG. 1 is an explanatory view showing a gas turbine provided with a gas turbine blade having an abrasive film formed on a tip portion by a film forming method according to the present invention.

Claims (27)

A method of forming a film,
A lamination step of laminating a brazing material layer containing a brazing material as a main component on a surface of a film formation target, and a covering material layer containing a coating material as a main component,
A melting step of heating the laminated brazing material layer and the coating material layer to melt at least a part of the coating material while diffusing the brazing material component into the coating material;
A fixing step of solidifying the molten coating material and fixing the coating material to the film formation target;
A method for forming a film, comprising: The film forming method according to claim 1, wherein a thickness ratio of the brazing material and the coating material laminated in the laminating step is 30/70 or more and 70/30 or less. 3. The method according to claim 1, wherein the brazing material component diffused into the coating material is boron. The film forming method according to any one of claims 1 to 3, wherein the brazing material is selected from a material having a melting point lower than a heat treatment temperature of a film forming target. . The method according to any one of claims 1 to 4, wherein the coating material layer is obtained by dispersing coating material particles in a binder. The film forming method according to claim 5, wherein a mass ratio of the binder and the coating material particles is 15/85 or more and 2/1 or less. 7. The coating material layer according to claim 1, wherein the coating material layer is mainly composed of MCrAlY particles, cubic boron nitride, Al ₂ O ₃ , TiN and other abrasive particles. 3. The method for forming a film according to item 1. The method according to claim 7, wherein a volume ratio of the MCrAlY particles to the abrasive particles is not less than 1/2 and not more than 2/1. 9. The method according to claim 7, wherein the object on which the film is formed is a tip of a moving blade of a gas turbine. 10. The method according to claim 7, further comprising, after the fixing step, an exposing step of removing part of MCrAlY from the surface of the fixed coating material layer to expose abrasive particles. 2. The method for forming a film according to claim 1. The method according to claim 10, wherein the exposing step is performed by blasting. The film forming method according to claim 11, wherein in the blasting, a blast material that is harder than the MCrAlY particles and softer than the abrasive particles is used. 13. The film forming method according to claim 12, wherein a particle size of the blast material is smaller than a particle size of the abrasive particles and smaller than an interval between the abrasive particles. The method according to any one of claims 1 to 6, wherein the coating material layer mainly includes MCrAlY particles. The method for forming a film according to claim 14, wherein the object on which the film is formed is a moving blade, a stationary blade, or a shroud of a gas turbine. A coating material for forming a film, comprising: cubic boron nitride, Al ₂ O ₃ , TiN, and other abrasive particles, a metal material having at least oxidation resistance, and a binder. 17. The film forming film according to claim 15, wherein a ratio of the mass of the binder to the mass of the abrasive particles and the metal material is 15/85 or more and 2/1 or less. Coating material. The coating material for forming a film according to any one of claims 15 to 17, wherein the metal material is MCrAlY. 19. The coating material according to claim 18, wherein a volume ratio of the MCrAlY particles to the abrasive particles is 1/2 or more and 2/1 or less. A polishing film-forming sheet, comprising a brazing material and a film-forming coating material according to any one of claims 15 to 19. 21. The sheet for forming an abrasive film according to claim 20, wherein a thickness ratio of the brazing material to the coating material for forming a film is 30/70 or more and 70/30 or less. 22. The sheet for forming an abrasive film according to claim 20, wherein the brazing material contains boron. The abrasive film according to any one of claims 20 to 22, wherein the brazing material is selected from a material having a melting point lower than a heat treatment temperature of a film formation target. Forming sheet. 24. The sheet for forming an abrasive film according to claim 23, wherein an adhesive layer is formed on the brazing material. A blade of a gas turbine, wherein a coating is formed on a tip portion by the coating forming method according to any one of claims 7 to 13. A blade of a gas turbine, wherein the sheet for forming an abrasive film according to any one of claims 20 to 24 is attached to a tip portion. A compressor that compresses air to produce combustion air,
A combustor that generates high-temperature combustion gas by reacting combustion air and fuel produced by the compressor;
A turbine having the moving blade according to claim 25, and driven by being injected with combustion gas from the combustor to the moving blade,
A gas turbine comprising:

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